pendsv, clock lib

Makefile

@@ -5,6 +5,7 @@ all:
 	arm-none-eabi-as $(MCUFLAGS) startup_stm32l476xx.s -c -o out/startup_stm32l476xx.o
 	arm-none-eabi-gcc $(CFLAGS) system_stm32l4xx.c -c -o out/system_stm32l4xx.o
 	arm-none-eabi-gcc $(CFLAGS) stm32l4xx_it.c -c -o out/stm32l4xx_it.o
+	arm-none-eabi-gcc $(CFLAGS) clock.c -c -o out/clock.o
 	arm-none-eabi-gcc $(CFLAGS) main.c -c -o out/main.o
 	arm-none-eabi-gcc $(CFLAGS) -T link.ld out/*.o -o out/main.elf
 	arm-none-eabi-objcopy -O ihex out/main.elf main.hex

clock.c

@@ -0,0 +1,59 @@
+#include <clock.h>
+#include <stm32l476xx.h>
+
+#define STK_CTRL	*((uint32_t *)0xE000E010)
+#define STK_LOAD	*((uint32_t *)0xE000E014)
+#define STK_VAL		*((uint32_t *)0xE000E018)
+#define STK_CALIB	*((uint32_t *)0xE000E01C)
+
+// ticks since init
+static uint32_t ticks = 0;
+
+void clock_init(void)
+{
+	// turn on HSI (16MHz)
+	RCC->CR |= RCC_CR_HSION;
+	while ((RCC->CR & RCC_CR_HSIRDY) != RCC_CR_HSIRDY);
+
+	// get PLLR to 80MHz (max)
+	// VCO = C * (N/M) -> 16 * (10/1) = 160
+	// SCLK = VCO / R = 160 / 2 = 80 MHz
+	RCC->PLLCFGR &= ~(RCC_PLLCFGR_PLLSRC);
+	RCC->PLLCFGR |= RCC_PLLCFGR_PLLSRC_HSI;
+	RCC->PLLCFGR &= ~(RCC_PLLCFGR_PLLN | RCC_PLLCFGR_PLLM);
+	RCC->PLLCFGR |= 10 << RCC_PLLCFGR_PLLN_Pos;
+	RCC->PLLCFGR &= ~(RCC_PLLCFGR_PLLR);	// /2
+	RCC->PLLCFGR |= RCC_PLLCFGR_PLLREN;		// PLLR on
+
+	// start PLL
+	RCC->CR |= RCC_CR_PLLON;
+	while ((RCC->CR & RCC_CR_PLLRDY) != RCC_CR_PLLRDY);
+
+	// set system clock to PLL
+	RCC->CFGR &= ~(RCC_CFGR_SW);
+	RCC->CFGR |= RCC_CFGR_SW_PLL;
+	while ((RCC->CFGR & RCC_CFGR_SWS_PLL) != RCC_CFGR_SWS_PLL);
+
+	// SysTick init. 80MHz / 80000 = 1kHz, ms precision
+	STK_LOAD = 80000;
+	STK_CTRL |= 0x07; // no div, interrupt, enable
+}
+
+void delay(uint32_t count)
+{
+	uint32_t target = ticks + count;
+	while (ticks < target);
+}
+
+void PendSV_Handler(void) {
+}
+
+void SysTick_Handler(void)
+{
+	// just keep counting
+	ticks++;
+
+	if (!(ticks % 500))
+		SCB->ICSR |= SCB_ICSR_PENDSVSET_Msk; 
+}
+

include/clock.h

@@ -0,0 +1,16 @@
+#ifndef CLOCK_H_
+#define CLOCK_H_
+
+#include <stdint.h>
+
+/**
+ * Sets HCLK (system clock) to 80MHz, the maximum.
+ */
+extern void clock_init(void);
+
+/**
+ * Sleeps for given milliseconds.
+ */
+void delay(uint32_t ms);
+
+#endif // CLOCK_H_

include/stm32l476xx.h

@@ -18497,6 +18497,30 @@ typedef struct
 #define DFSDM2_IRQHandler              DFSDM1_FLT2_IRQHandler
 #define DFSDM3_IRQHandler              DFSDM1_FLT3_IRQHandler
 
+/*typedef struct {
+	uint32_t CPUID;
+	uint32_t ICSR;
+	uint32_t VTOR;
+	uint32_t AIRCR;
+	uint32_t SCR;
+	uint32_t CCR;
+	uint32_t SHPR1;
+	uint32_t SHPR2;
+	uint32_t SHPR3;
+	uint32_t SHCRS;
+	uint32_t CFSR;
+	uint32_t HFSR;
+	uint32_t rsvd;
+	uint32_t MMAR;
+	uint32_t BFAR;
+	uint32_t AFSR;
+} __attribute__ ((packed)) SCB_TypeDef;
+
+#define SCB_ADDR	(0xE000ED00)
+#define SCB			*((SCB_TypeDef *)SCB_ADDR)
+
+#define SCB_ICSR_PENDSVSET		(1 << 28)*/
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */

main.c

@@ -1,16 +1,10 @@
-#include "stm32l476xx.h"
+#include <stm32l476xx.h>
-
+#include <clock.h>
-#define STK_CTRL	*((uint32_t *)0xE000E010)
-#define STK_LOAD	*((uint32_t *)0xE000E014)
-#define STK_VAL		*((uint32_t *)0xE000E018)
-#define STK_CALIB	*((uint32_t *)0xE000E01C)
-
-extern void delay(uint32_t count);
 
 /**
  * Accomplishments:
  *   - GPIO in/out
- *   - got to 40MHz clock
+ *   - got to 80MHz clock
  */
 
 void pulse(uint8_t byte);
@@ -21,50 +15,23 @@ int main(void)
 	FLASH->ACR &= ~(FLASH_ACR_LATENCY);
 	FLASH->ACR |= FLASH_ACR_LATENCY_2WS;
 
-	// turn on HSI
+	clock_init();
-	RCC->CR |= RCC_CR_HSION;
-	while ((RCC->CR & RCC_CR_HSIRDY) != RCC_CR_HSIRDY);
-
-	// get PLLR to 80MHz (max)
-	// VCO = C * (N/M) -> 16 * (10/1) = 160
-	// SCLK = VCO / R = 160 / 4 = 40 MHz
-	RCC->PLLCFGR &= ~(RCC_PLLCFGR_PLLSRC);	// source HSI, 16MHz
-	RCC->PLLCFGR |= RCC_PLLCFGR_PLLSRC_HSI;
-	RCC->PLLCFGR &= ~(RCC_PLLCFGR_PLLN | RCC_PLLCFGR_PLLM);
-	RCC->PLLCFGR |= 10 << RCC_PLLCFGR_PLLN_Pos;
-	RCC->PLLCFGR &= ~(RCC_PLLCFGR_PLLR);	// /4
-	RCC->PLLCFGR |= 1 << RCC_PLLCFGR_PLLR_Pos;
-	RCC->PLLCFGR |= RCC_PLLCFGR_PLLREN;		// PLLR on
-
-	// start PLL
-	RCC->CR |= RCC_CR_PLLON;
-	while ((RCC->CR & RCC_CR_PLLRDY) != RCC_CR_PLLRDY);
-
-	// set system clock to PLL
-	RCC->CFGR &= ~(RCC_CFGR_SW);
-	RCC->CFGR |= RCC_CFGR_SW_PLL;
-	while ((RCC->CFGR & RCC_CFGR_SWS_PLL) != RCC_CFGR_SWS_PLL);
-
-	// SysTick setup? Assume 4MHz reset clock
-	STK_LOAD = 40000;
-	STK_CTRL |= 0x07; // AHB, inten, enable
 
 	RCC->AHB2ENR |= RCC_AHB2ENR_GPIOAEN;	// A clk enable
-	GPIOA->MODER &= ~(GPIO_MODER_MODE5 | GPIO_MODER_MODE0);	// A5 -> output, A0 input
+	GPIOA->MODER &= ~(GPIO_MODER_MODE5 | GPIO_MODER_MODE6);	// A5 -> output, A0 input
-	GPIOA->MODER |= GPIO_MODER_MODE5_0;
+	GPIOA->MODER |= GPIO_MODER_MODE5_0 | GPIO_MODER_MODE6_0;
-	GPIOA->PUPDR &= ~(GPIO_PUPDR_PUPD5 | GPIO_PUPDR_PUPD0);
+	GPIOA->PUPDR &= ~(GPIO_PUPDR_PUPD5 | GPIO_PUPDR_PUPD6);
-	GPIOA->PUPDR |= GPIO_PUPDR_PUPD5_0 | GPIO_PUPDR_PUPD0_1; // pd for button
+	GPIOA->PUPDR |= GPIO_PUPDR_PUPD5_0 | GPIO_PUPDR_PUPD6_0; // pulldown for button (1)
-
+	//if (GPIOA->IDR & 0x01)
-	pulse(*((uint8_t *)0x08080000)); // 0b00100101
 
-	while (1);/* {
+	while (1) {
 		delay(500);
-		//if (GPIOA->IDR & 0x01)
 		GPIOA->BSRR |= 1 << 5;
+		GPIOA->BRR |= 1 << 6;
 		delay(500);
-		//else
+		GPIOA->BSRR |= 1 << 6;
 		GPIOA->BRR |= 1 << 5;
-	}*/
+	}
 }
 
 void _exit(int code)

stm32l4xx_it.c

@@ -1,13 +1,5 @@
 #include <stdint.h>
 
-static uint32_t ticks = 0;
-
-void delay(uint32_t count)
-{
-	uint32_t target = ticks + count;
-	while (ticks < target);
-}
-
 void NMI_Handler(void) {}
 
 void HardFault_Handler(void)
@@ -34,10 +26,3 @@ void SVC_Handler(void) {}
 
 void DebugMon_Handler(void) {}
 
-void PendSV_Handler(void) {}
-
-void SysTick_Handler(void)
-{
-  ticks++;
-}
-